1. Field
The field generally relates to a sputtering system, and more particularly, to a sputtering system configured to achieve uniform sputtering and deposition.
2. Description of the Related Technology
There are sputtering methods used for forming an inorganic layers such as metal layers, transparent conductive layers, or the like. In these sputtering methods, a rare gas such as argon (Ar) gas is introduced into a vacuum vessel, and a direct current (DC) voltage or a radio frequency (RF) voltage of more than 150 V is supplied to a cathode including a sputtering deposition material plate, and a layer is formed through slow discharge of the gas.
Sputtering methods are generally used in a layer forming process during manufacturing of flat panel display (FPD) devices, such as to form a thin film transistor (TFT) liquid crystal display (LCD) device or an organic electroluminescent light emitting display device, or various other electronic devices. These sputtering methods are classified as dry process techniques, and have a wide range of applications.
When an inert gas such as Ar, for example, which is used for a plasma source, is ionized, the surface of a deposition material plate is pressurized, and when the material is vaporized, reflection may occur. Also, when an oxide-based material is sputtered, anions of oxygen or other molecules with large energy reach a deposition substrate due to a strong repulsive force from a cathode. In these sputtering methods, particles are in a high-energy state of several eV or more. When particles with large kinetic energy reach the deposition substrate, the surface of the deposition substrate may be damaged, or a thin film formed on the surface of the substrate may be sputtered.
For example, when an inorganic layer is sputtered on an organic layer, so as to form upper electrodes of organic electroluminescent light emitting display devices, or electrodes of organic thin film transistors, particles having high energy of 100 eV or more generated in the sputtering processes collide with the organic layer and damage the organic layer.
In order to reduce such damage to the organic layer, some existing systems and processes attempt to intercept the access of ions by disposing a grid having a predetermined electric potential between the deposition material plate and the deposition substrate. Other existing systems and processes attempt to minimize the effect of plasma by applying a bias voltage to the deposition substrate; such systems may not completely eliminate the effect of the plasma.